For the crostini: – olive oil divided – onion – sugar – salt – balsamic vinegar – cremini mushrooms or other mushrooms of your choice – thyme – garlic minced – baguette  – cup vegan mozzarella shreds for alternatives, see notes – Salt and freshly ground black pepper to taste For the balsamic-Dijon dressing: – Maille Dijon Originale Mustard – extra virgin olive oil – balsamic vinegar